Method and system for milling a fuel for an oxy-fuel combustion burner

Abstract

The present disclosure relates to a method of milling a fuel for an oxy-fuel combustion burner, the method includes: separating air into a hot nitrogen gas stream, having a temperature of at least 150° C. and a purity of at least 98 mol-% nitrogen, and an oxygen gas stream; leading at least a part of the nitrogen gas stream to a fuel mill; milling the fuel by means of the fuel mill in a nitrogen rich atmosphere formed by means of the nitrogen gas stream; leading the at least a part of the nitrogen gas stream away from the milled fuel; leading the oxygen gas stream to the oxy-fuel combustion burner; conveying the milled fuel to the oxy-fuel combustion burner; and burning the fuel, by means of the oxy-fuel combustion burner, in an oxygen rich atmosphere formed by means of the oxygen gas stream. The present disclosure further relates to a system for milling a fuel for an oxy-fuel combustion burner as well as to a power plant comprising such a system.

1 . A method of milling a fuel for an oxy-fuel combustion burner, the method comprising:
 separating air into a hot nitrogen gas stream, having a temperature of at least 150° C. and a purity of at least 98 mol-% nitrogen, and an oxygen gas stream;   leading at least a part of the nitrogen gas stream to a fuel mill;   milling the fuel by means of the fuel mill in a nitrogen rich atmosphere formed by means of the nitrogen gas stream;   leading the at least a part of the nitrogen gas stream away from the milled fuel;   leading the oxygen gas stream to the oxy-fuel combustion burner;   conveying the milled fuel to the oxy-fuel combustion burner; and   burning the fuel, by means of the oxy-fuel combustion burner, in an oxygen rich atmosphere formed by means of the oxygen gas stream.   
     
     
         2 . The method of  claim 1 , wherein the air separating comprises cryogenic distillation. 
     
     
         3 . The method of  claim 1 , wherein the air separating comprises adiabatic compression of air to form an air stream having a temperature of at least 150° C. 
     
     
         4 . The method of  claim 1 , wherein the leading away of the hot nitrogen gas stream comprises removing any fuel particles from the hot nitrogen gas stream by means of a particle remover, such as an electrostatic precipitator or a cyclone. 
     
     
         5 . The method of  claim 1 , further comprising:
 leading a second part of the hot nitrogen gas stream to a fuel dryer;   drying the fuel by means of the fuel dryer, before or after the milling of said fuel; and   leading the second part of the hot nitrogen gas stream away from the dried fuel.   
     
     
         6 . A system comprising:
 an air separation unit arranged for separating air into a hot nitrogen gas stream having a temperature of at least 150° C. and a purity of at least 98 mol-% nitrogen, and an oxygen gas stream;   a fuel mill, arranged for milling a fuel in a nitrogen rich atmosphere formed by means of the nitrogen gas stream; and   an oxy-fuel combustion burner, arranged for burning the milled fuel in an oxygen rich atmosphere formed by means of the oxygen gas stream.   
     
     
         7 . The system of  claim 6 , wherein the air separation unit comprises a cryogenic distillation unit. 
     
     
         8 . The system of  claim 6 , wherein the air separation unit comprises an adiabatic compressor arranged for compressing air to form an air stream having a temperature of at least 150° C. 
     
     
         9 . An oxy-fuel combustion power plant comprising the system of  claim 6 .